The danger is in thinking that the holiness given you in Christ is not whole, perfect, complete. It IS. It is not at all so much the case that holiness grows in you, but that you grow in holiness. The gift is given: now we make progress in learning to live from it, so that love becomes ever more our life. "Progress" is okay concept in such a scenario. Old Martin Chemnitz used it:
"The healing and renewal itself is not such a change that is immediately accomplished and finished in a moment, but it has its beginnings and certain progress by which it grows in great weakness, is increased and preserved." Examen I:424
"The renewal of the new man, as also the mortification of the old, is not perfect and complete in this life but that it grows and is increased day by day until it is perfected in the next life, when this corruptible will have put on incorruption." Examen I:538
"But men are to be admonished that they should through the Spirit mortify the deeds of the flesh and firmly adhere to Christ by faith and through the use of the Word and of the Sacraments become more and more united with Him and seek from God the gift of perseverance, and wrestle, lest the wantonness of the flesh drive out the gift of perseverance." Examen I:607
More and more united. With Christ. So that repentance means turning away from the life that is in Adam (a dead end road if ever there were one) and growing into the freedom given in Christ. "Unbending" us, if you will, and opening our eyes to believe and live from the gift.
I think that's why St. Peter said after that long list of virtues that need to be ours and increasing, that if they are not, the problem isn't with our good works, but with our faith: "Whoever lacks these qualities is so nearsighted that he is blind, having forgotten that he was cleansed from his former sins." (2 Pet 1:9)
This particular point is one that Schmemann nailed:
"And the holiness of the Church is not our holiness, but Christ's, who loved the Church and gave Himself for her 'that He might sanctify her...that she might be holy and without blemish' (Eph 5:25-27). Likewise the holiness of the saints as well is but the revelation and the realization of that sanctification, that holiness that each of us received on the day of baptism, and in which we are called to increase. But we could not grow in it, if we did not already possess it as a gift of God, as his presence in us through the Holy Spirit." (Schmemann, Eucharist, pp. 23, 24)
The gift is given whole: the Holy Spirit gives us the gift of Christ Himself to be our all - sanctification is the life of appropriating that gift ever more and more, turning away from the old self and finding life in union with Him who is our Life. Thoughts?